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The present study investigated the performance of iron ore mixed with carbide slag (CS) as oxygen carrier in a batch-fluidized bed reactor using Datong bituminous coal as fuel. The effects of mixing mass ratio and reaction temperature on the CLC process of coal were investigated. The results showed that iron ore mixed with carbide slag accelerated the CLC process of coal compared with iron ore alone. Reaction temperature had a crucial effect on carbon conversion of coal, but higher than 900°C resulted in a decreased reactivity of CS-mixed oxygen carrier. Multiple redox cycle tests were also conducted to study the stability of CS-mixed oxygen carrier. It was found that though a continuing decreasing reactivity was observed for CS-mixed oxygen carrier, it still has higher CO2 yield and lower CO yield than those of undecorated one. SEM analysis revealed that sintering occurred on the surface of CS-mixed oxygen carrier, resulting in the deterioration of reactivity. The reason for the promoted performance of CS-mixed iron ore seems to be the catalytic effect of carbide slag on the water-gas shift reaction, converting CO to H2, for H2 is more reactive toward iron ore. [ABSTRACT FROM AUTHOR]

Underground coal gasification is a complex physico-chemical process. UCG thermodynamic equilibrium model was established and validated, and the effects of the steam-to-oxygen ratio (RH2O/O2) and the equivalence ratio (ER) on the gasification temperature and the gaseous products were investigated. At low ER (0.08–0.14), coal is incompletely gasificated when the gasification temperature is less than the corresponding peak temperature. At high ER (0.16–0.30), coal is completely gasificated. With the increase of RH2O/O2, the gasification temperature decreases monotonically and finally tends to approach 850°C at RH2O/O2 = 4.5. H2 reaches high concentration at ER = 0.18–0.24 and RH2O/O2 = 1–3, but the change of CH4 concentration is just the opposite. CO concentration is high at RH2O/O2<1.5. In order to reach high the utilization effectiveness of oxygen, RH2O/O2 has the corresponding optimum value where the utilization effectiveness of oxygen reaches peak value at ER = 0.08–0.2. [ABSTRACT FROM AUTHOR]

Supercritical water (SCW) gasification technology can enable the efficient utilization of coal by converting it to hydrogen-rich gas. However, poly-cyclic aromatic hydrocarbons and heavy components, which are intermediates of supercritical water gasification, tend to generate char, hindering the complete gasification of coal. In this work, phenol is recycled to enhance the gasification process and reduce the formation of these intermediates during SCWG, and the regulation mechanism is investigated. The results demonstrate that both gas yield and gasification efficiency increase with the presence of phenol, reaching approximately 98.5% at 750 °C, concentration of 2%with the effect of phenol, which is 27% higher than that in the coal-water system. Organics removal rate reaches about 98% with the addition of phenol. Phenol can enhance the gasification performance by facilitating the conversion of heavy components to lightweight components. The transient reactivity of coal in the poly-condensation stage is increased by about 50 times with the presence of phenol. The regulation mechanism of phenol in the poly-condensation stage during coal gasification involves the decomposition of SCW forming hydroxyl radicals, which replaces the substituents on the benzene ring, facilitating the dissociation of benzene ring into small molecules that are prone to polymerize. The interacting force between phenol and multi-rings disrupts the conjugate structure, aiding in the decomposition of polycyclic organics into small molecules. • Investigated the regulating mechanism of phenol on the gasification process. • Hydrogen yield and gasification efficiency increases with the presence of phenol. • Nearly complete gasification (98.5%) is realized with the presence of phenol. • The organics removal rate reaches about 98% with the presence of phenol. • Reactivity of coal in the polycondensation stage increased by 50 times with phenol. [ABSTRACT FROM AUTHOR]

To solve the problem of controlling the stability of small coal pillars under the mining disturbance of the adjacent working face, the fourth panel 403 and 404 working faces of the Gaojiabao coal mine with two mining roadways is taken as the object of this research. The comprehensive research method of combining mechanical theory analysis, coal dynamic disturbance experiments and field engineering practice was adopted. First, the analysis determined the magnitude and frequency of fracture‐related disturbance loading on the overburden roof of the working face; next, the strain and stress threshold indicators of the coal body, sensitive to the external disturbance load of 103 J magnitude (continuous disturbance deformation), were tested and obtained through a self‐developed rock creep disturbance experimental system, and the stress threshold indicators of coal body specimens sensitive to creep disturbance were defined as the long‐term strength. Then, a coal pillar‐roof mechanics structure model was established in the premining and postmining areas of the working face, and the overlying support pressure on the coal pillar body was analysed. Finally, a small coal pillar composite reinforcement support technology with 'two‐way buttressing anchor cable for pressure reinforcement + steel pipe concrete pier column + overhead roof break' was designed to ensuring that the coal pillar body would not be destabilised by cumulative disturbance and large deformation under disturbance. According postmining area support capacity calculations, the support loading acting on the coal pillar is approximately 17593 kN, with the stress being 2.93 MPa; and the factor of safety is approximately 1.23. After engineering practice application of this approach, the vertical deformation of the small coal pillar body and side heave disturbance deformation were effectively controlled during the working face mining disturbance, the vertical deformation of the reinforced coal pillar was only 187 mm, and the side heave deformation was finally stabilised at approximately 124 mm, which maintained good stability. [ABSTRACT FROM AUTHOR]

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This work assessed some properties and effects of biocoal briquettes on environmental pollution compared with utilising coal alone. A mixture of coal fines and rice husks was prepared, with cassava starch gel as a binder, before compaction in a briquetting machine and drying with a solar dryer. Samples of the coal fines, rice husk, cassava flour and briquettes were analysed for their elemental and oxide concentrations via an energy-dispersive X-ray fluorescence analyser. The heat fuels were analysed for their thermal behaviour via thermogravimetric analyser (TGA), whereas the specific surface area, pore size and pore volume were determined using a Brunner–Emmett–Teller (BET) analyser. The conversion of the tested coals to biocoal briquettes resulted in a reduction in the level of arsenic in the briquettes. Additionally, the sulphur level decreased from 1.96 to 1.11% in the Okobo-Enjema briquettes and from 1.78 to 0.90% in the Onyeama briquettes. However, the levels of manganese increased from 0.04 to 0.22% in the Okobo-Enjema briquettes and from 0.04 to 0.21% in the Onyeama briquettes. Thermogravimetric analysis at different heating rates revealed that derivative weight loss increased with increasing heating rate, from 4.4% at 10 °C/min to 5.5% at 20 °C/min. BET analysis revealed that the briquettes had larger pore diameters, volumes and specific surface areas than did the coal samples. The coal samples have greater propensity to pollute the environment as the amount of potentially hazardous elements in the samples is greater than in their biocoal briquettes. [ABSTRACT FROM AUTHOR]

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Coal gasification to manufacture dihydrogen (H 2) has long been known as a surface process. Recent works have also highlighted the H 2 generating potential of the Organic Matter (OM). The evolution of OM generates H 2 all along the process but this gas is only expected to remain as free H 2 after the maturation and expulsion of the hydrocarbons (HC) which means at a high temperature of above 200 °C. In this paper we studied the potential of three different tertiary coals from Amaga, La Jagua de Ibirico and Barrancas, all located in Colombia. Their H 2 yields were studied using a pyrolyser and the kinetic of the H 2 generation were quantified. All the studied coals are immature to early mature as source rock (SR) with large TOC content, between 66 and 83%, and good H 2 potential. The highest values were found for the Barrancas area where the potential reached 25 mg H 2 /g TOC. The temperature corresponding to the peak of H 2 generation is between 740 and 800 °C depending of the heating rate. This corresponds to the 200–300 °C for the H 2 kitchen, even if the H 2 generation starts before as already observed for continental organic rich source rock. Comparison with the other coals shows that H 2 potential is linear with TOC. In the Colombian coals, the H 2 yield in mg H 2 /g of rock is around 1/4 of the TOC content. In average, these coals have so a H 2 yield about 10 000 mmol H 2 /kg of rock, two orders of magnitude above the "best" olivines. It should nevertheless be kept in mind that the extrapolation of these laboratory data to sedimentary basins remains unconstrained and will need to be refined when well data and modelling tools are available. • The coals have significant H 2 potential in deep sedimentary basins. • High temperature open-system pyrolizer can be used to quantify these H 2 yield. • The reaction kinetic of the H 2 generation from coal is of order 1 and H 2 window generation can extend from 200 to 400 °C. • The Cenozoic Colombian coal's yield of H 2 in mgH 2 /g rock is ca ¼ of its organic carbon content in percentage. • A 80% TOC rich coal has a H 2 yield two orders of magnitude higher than that of olivines at a similar temperature of 250 °C. [ABSTRACT FROM AUTHOR]

South Africa is an energy-intensive developing country in Africa and ranked as the 1st and 14th emitter of greenhouse gas (GHG) in Africa and the world, respectively. The abundance and availability of coal in South Africa make it the mainstay primary source of energy contributing 56% of national total GHG emissions. This paper focused on the duo of energy generation and emission associated with coal processing and utilization in South Africa, and the urgent need to advance coal processing technologies marked by high carbon footprints in consonance with the sustainable development goals. Different gasification techniques and their performances have been compiled and discussed. The economic, environmental impact, energetic, and exergetic characteristics of existing hydrogen production technologies for renewable and non-renewable energy sources have been examined along with hydrogen production from plasma gasification of coal. Hydrogen production via coal or coal/biomass plasma gasification technology (nuclear-, wind-, PV solar-, and concentrated solar power-driven) in addition to carbon capture technology for transforming the captured CO 2 into value-added products appears to be the most viable option to considerably reduce emissions and meet the energy demand of South Africa. This proposed technology can be pivotal to achieving a low-carbon economy (medium-term) and transition to hydrogen economy (long-term) as championed by the global sustainable development agenda. Conclusively, hydrogen (stored in different forms e.g., liquid hydrogen, ammonia, and organic hydride) seems to find more applications (in the space industry, transport, energy storage, defense industry, etc.) than coal owing to its immediate use in distribution/demand centers and remote areas. • Coal is the primary energy source of South Africa and key driver of national CO 2 emissions. • Traditional coal gasification technologies are marked by high CO 2 emissions. • Coal plasma gasification technology is a viable option for low-carbon energy economy. • Hydrogen production via coal or coal/biomass plasma gasification technology leads to zero-carbon economy. • This immensely supports the drive towards attaining the sustainable development goals. [ABSTRACT FROM AUTHOR]

The molecular structure of coal is complex, and the existing research methods are limited, so it is difficult to clarify its influence mechanism on the spontaneous-combustion characteristics of coal. In this paper, the previous extraction, FTIR, TPR, TG-DSC and other experimental results are combined to analyze the extraction weakening effect and the correlation analysis of the spontaneous-combustion characteristic parameters of raffinate coal. The results show that extraction can destroy the connection bond of coal molecules, change the content of dominant active groups in the coal spontaneous-combustion reaction, increase the lower limit of the key temperature nodes of coal spontaneous-combustion or extend the temperature range, resulting in an increase in the ignition-point temperature of coal and a decrease in coal quality. This paper will provide a theoretical basis for the study of the microscopic mechanism of coal spontaneous-combustion and then provide new ideas for the development of an active prevention and control technology for coal spontaneous-combustion. [ABSTRACT FROM AUTHOR]

Coal is the most valuable gasification resource due to its abundance and low cost for commercial applications. But utilization of low-rank Indian coals for gasification is challenging due to difficulty in washing. For utilizing low-grade high ash raw coal, blending is one of the effective methods to control the gasification performances. So, the present study explores the gasification of such a low-rank raw coal blend and compares the results with washed coal blend. The blending effects on raw gas yield (kg/kg of coal) and heating value (Kcal/Nm3) were investigated for coal blends-WH (washed coal with high-rank coal) and RH (raw coal with high-rank coal). In WH, raw gas yield is 1.210 to 1.225 (kg/kg of coal), whereas, in RH is 1.189 to 1.213 (kg/kg of coal), though the fixed carbon content of WH (40.75–41.74%) is lower than RH (44.73–45.25%). In washed coal, raw gas yield is minimum (0.75 kg/kg of coal). The heating value is lower in WH (2730–2871 Kcal/Nm3) than in RH (2884–2978 Kcal/Nm3). Statistical correlation is developed between gaseous components of raw gas and heating value; H2/CO ratio is the most significant parameter. RH gasification is economically viable than WH. [ABSTRACT FROM AUTHOR]

Copyright of Rudarsko-Geolosko-Naftni Zbornik is the property of Faculty of Mining, Geology & Petroleum Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lock-in to existing assets and business practices is a major obstacle to the global objective of phasing out coal-fired power to accelerate decarbonization towards Paris Agreement goals. Japan has attracted attention in previous literature, with several studies demonstrating how market and political conditions have propelled investments in new coal-fired power plants while raising barriers to achieving a phase-out. But in addition to market-level conditions, firm-level characteristics – including assets, commitments, investment behaviour and future-oriented innovation activities – are also critical determinants of lock-in vulnerability. To deepen understanding of how such firm-level dynamics might affect the power industry, this empirical study takes the case of ten incumbent utilities in Japan to identify and compare potential sources of coal lock-in. We leverage diverse quantitative and qualitative data to assess the state of: (1) management, assets and operational factors; and (2) the development and deployment of next-generation coal technologies. Through this two-fold approach, we demonstrate how current conditions and future-oriented activities are likely to reinforce tendencies to continue using coal in coming decades, thereby hampering the emergence of phase-out ambitions. These findings harbour important implications for climate policy and the urgent need to end coal burning in the power sector. Japan's major power utilities all intend to maintain coal in power mixes while transitioning to net-zero by 2050, aiming to eliminate carbon emissions rather than coal-fired power per se. Ambitions to reduce dependence on coal are weakened by a multitude of potential lock-in sources across individual utilities. All utilities are attempting to commercialize next-generation technologies such as co-firing with ammonia and biomass, carbon capture and coal gasification. Phasing out coal in Japan thus requires climate policies that incentivize the development and diffusion of non-emitting power sources that offer faster emissions reduction than expensive and unproven technologies. [ABSTRACT FROM AUTHOR]

Context: Coal water slurry (CWS) is a new type of liquid coal product with low pollution, which is mainly used in the chemical industry to produce syngas (CO + H2). It is of great significance to study the microscopic mechanism of CWS gasification reaction for improving the efficiency of coal gasification. In this paper, the method of molecular dynamics based on reaction force fields (ReaxFF-MD) is used to study the gasification process of CWS/O2 system at different temperatures. The results show that, in the range of 1600–2400 K, the macromolecular network structure of lignite is decomposed into a large number of small molecular structures and a small number of light tar free radical fragments, and the types and quantities of reaction products increased rapidly. At 2400–4000 K, the free radical fragments of light tar are further decomposed and reacted with gasification agents, but the types and quantities of reaction products have little change. At 3600 K, a full gasification reaction occurred in the system, and the content of syngas is the highest. Methods: The model was established and optimized by Materials Studio (MS) software. Based on ReaxFF-MD method, Lammps software was used to simulate the gasification process of CWS/O2 system, and the reaction force field files containing C, H, O, N, and S element were used. By calculating the activation energy of gasification reaction, the rationality of the model and calculation method was illustrated. The post-processing of the results was implemented using OVITO, ChemDraw software, and self-programmed Python scripts. [ABSTRACT FROM AUTHOR]

The effects of coal gangue (CG) on the ash initial deformation temperature (IDT) and CO2 gasification characteristic of biomass (chestnut shell [CS] and soybean straw [SS]) were investigated by ash fusion tester and thermogravimetric analyzer, respectively. The IDTs of CS and SS ashes were low because of the presence of abundant low melting point (MP) airchildite (K2Ca(CO3)2) and arcanite (K2SO4), and they were efficiently improved by the CG additions of 2%–10% mass ratios. The increases in the IDTs of CS and SS ashes were resulted from the conversions of fairchildite and arcanite into high MP K‐Al silicates (kalsilite [KAlSiO4], leucite [KAlSi2O6], etc.). The gasification reactivities of CS/CG mixtures stayed below that of CS, and they decreased with increasing CG mass ratios (4%–10%) and increased with increasing temperatures (900–1000°C). At 900°C, CG addition caused a decrease in the gasification reactivity of SS. When the temperature reached 950°C, the CG addition of 4% mass ratio increased the gasification reactivity of SS instead. The synergistic effect between biomass and CG during cogasification was more significant at low CG mass ratio and high temperature, and the synergistic effect between SS and CG was more intense than that between CS and CG. [ABSTRACT FROM AUTHOR]

Modern coal chemical industry is an important means to realize the clean utilization of coal resources, the coal chemical sludge generated during the process of coal conversion process is a typical refractory solid waste restricting the development of coal chemical industry since its extremely high water content and the poor dewaterability. It has been documented that the dewaterability of coal chemical sludge is affected by the microbial community structure and water distribution characteristics; and thus, it is necessary to investigate the microbial community information and water distribution in coal chemical sludge to provide theoretical guidance for the high-efficiency sludge dewatering technology. In this study, coal-to-olefins sludge and coal-to-oil sludge were selected and the microbial community structure of the two sludge was obtained through analyzing 16s rRNA gene sequencing, and the water distribution was obtained by DSC and LF-NMR method. The results show that the different sewage treatment processes chosen by two coal chemical industries lead to certain differences in the microbial community structures of coal chemical sludge, Proteobacteria, Bacteroidetes and Chloroflexi are the dominant phylum in the two sludge. The LF-NMR method can more accurately measure the water distribution, and the water in the sludge can be classified into bound water, mechanical bound water and free water according. [ABSTRACT FROM AUTHOR]

The co-gasification of coal and biomass offers numerous benefits, including improved gasification efficiency, reduced pollution emissions, and the utilization of renewable resources. However, there is a lack of comprehensive research on the synergistic effects of, and influence parameters on, coal–biomass co-gasification. This study employs Aspen Plus simulations to investigate the co-gasification behavior of coal and corn straw, focusing on the synergistic effects and the impact of various operating conditions. A synergistic coefficient is defined to quantify the interactions between the feedstocks. Sensitivity analyses explore the effects of gasification temperature (800–1300 °C), coal rank (lignite, bituminous, anthracite), biomass mass fraction (0–50%), oxygen-to-carbon ratio, and steam-to-carbon ratio on the synergistic coefficients of effective syngas content (CO + H2), specific oxygen consumption, specific fuel consumption, and cold gas efficiency. The results reveal an optimal biomass mass fraction of 10% for maximizing cold gas efficiency, with the syngas primarily consisting of H2 (36.8%) and CO (61.6%). Higher gasification temperatures (up to 1200 °C) improve syngas quality and process efficiency, while higher-rank coals exhibit better gasification performance compared to lignite. Optimal oxygen-to-carbon and steam-to-carbon ratios are identified for maximizing syngas yield and quality. These findings provide valuable guidance for the design and optimization of industrial coal–biomass co-gasification processes, enabling the maximization of syngas quality, process efficiency, and resource utilization. [ABSTRACT FROM AUTHOR]

Coal catalytic hydrogasification (CCHG) is a straightforward approach for producing CH4, which shows advantages over the mature coal-to-CH4 technologies from the perspectives of CH4 yield, thermal efficiency, and CO2 emission. The core of CCHG is to make carbon in coal convert into CH4 efficiently with a catalyst. In the past decades, intensive research has been devoted to catalytic hydrogasification of model carbon (pitch coke, activated carbon, coal char). However, the chemical process of CCHG is still not well understood because the coal structure is more complicated, and CCHG is a combination of coal catalytic hydropyrolysis and coal char catalytic hydrogasification. This review seeks to shed light on the catalytic process of raw coal during CCHG. The configuration of suitable catalysts, operating conditions, and feedstocks for tailoring CH4 formation were identified, and the underlying mechanisms were elucidated. Based on these results, the CCHG process was evaluated, emphasizing pollutant emissions, energy efficiency, and reactor design. Furthermore, the opportunities and strategic approaches for CCHG under the restraint of carbon neutrality were highlighted by considering the penetration of "green" H2, biomass, and CO2 into CCHG. Preliminary investigations from our laboratories demonstrated that the integrated CCHG and biomass/CO2 hydrogenation process could perform as an emerging pathway for boosting CH4 production by consuming fewer fossil fuels, fulfilling the context of green manufacturing. This work not only provides systematic knowledge of CCHG but also helps to guide the efficient hydrogenation of other carbonaceous resources such as biomass, CO2, and coal-derived wastes. [ABSTRACT FROM AUTHOR]

Biogenic coalbed methane (BCBM) reservoirs aim to produce methane from in situ coal deposits following microbial conversion of coal. Success of BCBM reservoirs requires economic methane production within an acceptable timeframe. The work reported here quantifies the findings of previously published qualitative work, where it was found that bioconversion induces strains in the pore, matrix and bulk scales. Using imaging and dynamic strain monitoring techniques, the bioconversion induced strain is quantified here. To understand the effect of these strains from a reservoir geomechanics perspective, a corresponding poromechanical model is developed. Furthermore, findings of imaging experiments are validated using core-flooding flow experiments. Finally, expected field-scale behavior of the permeability response of a BCBM operation is modeled and analyzed. The results of the study indicated that, for Illinois coals, bioconversion induced strains result in a decrease in fracture porosity, resulting in a detrimental permeability drop in excess of 60% during bioconversion, which festers itself exponentially throughout its producing life. Results indicate that reservoirs with high initial permeability that will support higher Darcian flowrates, would be better suited for coal bioconversion, thereby providing a site-selection criteria for BCBM operations. [ABSTRACT FROM AUTHOR]

Coal fly ash (CF) is used in coal pyrolysis or gasification as a result of the high content of oxide metals. However, CaSO 4 and SiO 2 in CF inhibited catalytic activity. Herein, the application of acid-base modified CF to steam gasification of coal (CA). It was found that the order of acid-alkali modification had different effects on the H 2 production. NaOH–HF (A-E) modified CF, there was no CaSO 4 present on the surface of CF, and the surface SiO 2 shell structure was destroyed, releasing more α-Fe and α-Fe 2 O 3. A new Fe active phase (Fe x F y) had been formed. Meanwhile, the functional groups on the surface of modified CF changed, resulting in more C–H bonds, which provided more H sources for gasification. The α-Fe and α-Fe 2 O 3 in NaOH–HF modified CF were in full contact with coal and steam, breaking the O–H bonds in the H 2 O, the aliphatic side-chain hydrocarbons and C–H bonds in the coal to produce more H 2. α-Fe 2 O 3 and α-Fe undergoes mutual transformation at the action of H 2 , providing more Fe to increasing H 2 production. When the gasification temperature was 900 °C, the steam flow rate was 1 mL/min and the heating rate was 10 °C/min, the H 2 yield increased from 915.97 mL/g -(E-A) to 1539.72 mL/g -(A-E) , the carbon conversion of coal gasification was 99.68%. [Display omitted] • Release of catalytic activity of fly ash itself using NaOH–HF modification method. • The NaOH–HF modification method was used to reduce the content of CaSO 4 in CF. • The NaOH–HF modification method was used to change the original structure of the CF. • α-Fe and α-Fe 2 O 3 promotes the fracture of O–H bonds in H 2 O and C–H bonds in coal. • The modified fly ash enhances the generation of H 2 in coal under steam. [ABSTRACT FROM AUTHOR]

[Objective] Sludge production is abundant; however, its utilization rate remains low; co-gasification of sludge with coal is an important way to realize its resourcefulness and harmlessness. In industrial operations, gasification agents such as air and carbon dioxide primarily influence gasification, and the ash characteristics of the feedstock are crucial to ensure the long-term stable operation of the gasifier. The slagging characteristics of raw materials are closely related to their ash-melt properties, and the transformation of minerals is the essence of the change in the ash-melt properties. Currently, owing to the difference in the composition of raw materials, the evolutionary mechanism of the mineral transformation of the coal and sludge co-gasification process through the change in the sludge mixing ratio and the atmosphere on the mixing of the two remains unclear and lacks guidance for the change in the composition, which warrants further analysis. [Methods]In this paper, an experiment was designed for the mineral conversion and slagging characteristics analysis in the co-gasification process of coal and domestic sludge. The experiment involved the slagging characteristics of coal-sludge mixed samples, ash melting characteristics, and mineral conversion during co-gasification. Using anthracite and domestic sludge as raw materials, the two were mixed in different mass ratios. The characteristic temperature of ash melting was determined using an ash melting point tester. The basic-acid ratio, silica-aluminum ratio, and other evaluation criteria were used to evaluate the slagging characteristics. An oxidizing atmosphere and a weakly reducing atmosphere were employed as the environments for the co-gasification of coal and sludge, respectively. The high-temperature ash samples obtained from the co-gasification were characterized using X-ray diffractometry and Fourier transform infrared spectroscopy to analyze the changes in minerals. [Results] The experimental results revealed the following: 1) The characteristic temperature of coal ash melting remained higher. The characteristic temperature of ash melting decreased with increasing sludge mixing ratio. Among them, the melting characteristic temperature decreased most significantly when mixed with 20% sludge; 2) According to the discriminant indices such as alkaline-acid ratio, silica ratio, silica-aluminum ratio, and composite index, coal ash was associated with mild slagging, and domestic sludge ash belonged to severe slagging. After sludge mixing of over 50%, the mixed sample ash was associated with serious slagging; 3) The high content of mullite (Al6Si2O13) in coal ash was the primary reason for its high ash melting point. The blending of sludge increased the alkaline oxides such as CaO and MgO in the mixed samples, and the mullite content decreased rapidly, transforming into eutectics with lower melting points such as anorthite (CaAl2Si2O8). This was the main reason for the decrease in the melting temperature of the mixed ash sample; 4) Compared with the oxidizing atmosphere, the weak reducing atmosphere was more conducive to the formation of anorthite, and the coal could produce more anorthite by mixing a lower proportion of sludge. [Conclusions]Through this experiment, students can master the design method of mineral transformation and slagging characteristic experiment in the co-gasification process of coal and sludge mixed samples, which will help students to analyze and master the microscopic characterization methods and cultivate their innovative ability for the effective utilization of carbon-containing solid waste resources. [ABSTRACT FROM AUTHOR]

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To reduce pollution and improve the efficiency of coal resource utilization, this study proposed an integrated process for smelting reduction ironmaking and coal gasification. A multi-zone constrained mathematical model, based on heat and mass balance calculations, was developed to predict the energy and material flows required to produce 1 ton of hot metal. Two scenarios were examined: one using pure O2 as the gasification agent (referred to as the non-hydrogen-rich process) and the other using a combination of pure O2 and pure steam (referred to as the hydrogen-rich process). In the non-hydrogen rich process, as the PCR (Post Combustion Ratio) varies from 0% to 8%, the total coal consumption, O2 consumption, and volume of exported gas decrease by 57%, 57% and 53%, respectively. In the hydrogen-rich process, as the H2 content increases from 30% to 50%, the exported gas volume increases by 38%. The upper limit of H2 content in the SRV (Smelting Reduction Vessel) off-gas is mainly determined by the PCR, which decreases from 52.7% to 45.2% as the PCR varies from 0% to 8%. The findings of this work can serve as a theoretical basis for further investigation of the new process. [ABSTRACT FROM AUTHOR]

This paper focuses on the issues of sour water corrosion, CO2 corrosion, wet H2S corrosion, chloride ion corrosion, and stainless steel chloride stress corrosion cracking in gasification-scrubbing system of coal to hydrogen unit. The on-site corrosion monitoring results show that 15CrMo and 14CrlMo are belong to corrosion-resistant materials, while 06Crl3, S30403, S31603, and S22053 are fully corrosion-resistant materials. The laboratory corrosion evaluation results show that 15CrMo belongs to corrosion-resistant materials at less than 200 °C and non corrosion-resistant materials at not less than 200 °C; 06Crl3 is a good corrosion-resistant material at less than 250 °C, and a corrosion-resistant materials at not less than 250 °C; S30403, S31603, and S22053 are fully corrosion-resistant materials; chloride ions have a promoting effect on the corrosion of Q245R and 15CrMo. Based on the above researches, combined with the actual operation of the unit and engineering experience, a recommended plan for equipment and pipeline material selection has been developed, and corrosion control strategies have been proposed. [ABSTRACT FROM AUTHOR]

Coal gangue (CG) and coal gasification coarse slag (CGCS) possess both hazardous and resourceful attributes. The present study employed co-roasting followed by H2SO4 leaching to extract Al and Fe from CG and CGCS. The activation behavior and phase transformation mechanism during the co-roasting process were investigated through TG, XRD, FTIR, and XPS characterization analysis as well as Gibbs free energy calculation. The results demonstrate that the leaching rate of total iron (TFe) reached 79.93%, and Al3+ achieved 43.78% under the optimized experimental conditions (co-roasting process: CG/CGCS mass ratio of 8/2, 600 °C, 1 h; H2SO4 leaching process: 30 wt% H2SO4, 90 °C, 5 h, liquid to solid ratio of 5:1 mL/g). Co-roasting induced the conversion of inert kaolinite to active metakaolinite, subsequently leading to the formation of sillimanite (Al2SiO5) and hercynite (FeAl2O4). The iron phases underwent a selective transformation in the following sequence: hematite (Fe2O3) → magnetite (Fe3O4) → wustite (FeO) → ferrosilite (FeSiO3), hercynite (FeAl2O4), and fayalite (Fe2SiO4). Furthermore, we found that acid solution and leached residue both have broad application prospects. This study highlights the significant potential of co-roasting CG and CGCS for high-value utilization. [ABSTRACT FROM AUTHOR]

Coal samples from seams Ia, I, IIa+b, III, IV, and V from the Bobov Dol deposit in SW Bulgaria were studied using optical microscopy and proximate analysis in order to determine their suitability for fluidized-bed gasification. The moderate- to high seam averaged ash yields and the huminite reflectance values in the range 0.43-0.5 classify the studied coals as medium- to very low grade, low-rank A (sub-bituminous) according to the International classification of in-seam coals. Based on the organic composition and ash yields, the coals from seams IIa+b, III, IV, and V seem more suitable for fluidized-bed gasification, but their usefulness will depend largely on the coal pre-processing. [ABSTRACT FROM AUTHOR]

The coal gasification process produces a large amount of wastewater which is seriously polluted and difficult to biochemically treat. The regasification of coal water slurry produced from gasification wastewater meets the requirements of clean and efficient use of energy and the concept of circular economy. In this paper, the slurryability of coal water slurry prepared with gasification wastewater was measured, and the influence mechanism of organic matter, metal ions, and ammonia nitrogen components in coal gasification wastewater on slurryability has been studied. Results show that (a) Coal water slurry can be prepared with gasification wastewater, and the composition of wastewater has a great influence on the slurryability. (b) Phenols and alcohols in wastewater are not conducive to slurryability, while urethane in wastewater is beneficial for slurrying. (c) K+ and Na+ in wastewater have little effect on the slurryablity even in high concentration, while Mg2+ and Ca2+ have basically no effect on the slurryability under the concentration range of coal gasification wastewater. However, Fe3+ has a negative effect and Cu3+ has a positive effect on the slurryability at low concentrations. (d) Ammonia nitrogen can affect the slurryability of coal water slurry by affecting the pH of the solution. NH4OH solution is alkaline, which is conducive to slurrying, while (NH4)2SO4 and NH4Cl solutions are acidic, resulting in poor slurryability of coal water slurry. [ABSTRACT FROM AUTHOR]

The co-gasification of biomass and coal is helpful for achieving the clean and efficient utilization of phosphorus-rich biomass. A large number of alkali and alkaline earth metals (AAEMs) present in the ash system of coal (or biomass) cause varying degrees of ash, slagging, and corrosion problems in the entrained flow gasifier. Meanwhile, phosphorus is present in the slag in the form of PO 4 3 − , which has a strong affinity for AAEMs (especially for Ca2+) to produce minerals dominated by calcium phosphates or alkaline Ca-phosphate, effectively mitigating the aforementioned problems. To investigate the changing behavior of the slag flow temperature (FT) under different CaO/P2O5 ratios, 72 synthetic ashes with varying CaO/P2O5 ratios at different Si/Al contents and compositions were prepared, and their ash fusion temperatures were tested. The effects of different CaO/P2O5 ratios on the FT were analyzed using FactSage thermodynamic simulation. A model for predicting slag FT at different CaO/P2O5 ratios was constructed on the basis of the average molar ionic potential (Ia) method and used to predict data reported from 19 mixed ashes in the literature. The results showed that Ia and FT gradually increased with a decreasing CaO/P2O5 ratio, and the main mineral types shifted from anorthite → mullite → berlinite, which reasonably explained the decrease in ash fusion temperatures in the mixed ash. The established model showed good adaptability to the prediction of 19 actual coal ash FTs in the literature; the deviation of the prediction was in the range of 40 °C. The model proposed between FT and Ia based on the different CaO/P2O5 ratios can be used to predict the low-rank coal and phosphorus-rich biomass and their mixed ashes. [ABSTRACT FROM AUTHOR]

Underground coal gasification (UCG) is the process of directly recovering energy as combustible gases such as hydrogen and carbon monoxide by combusting unmined coal resources in situ. The UCG process is an invisible phenomenon, in which fracturing activity at high temperature (>1000 °C) in coal seams expands the gasification zone and increases the combustible components of the product gas. However, excessive expansion of the gasification zone may cause environmental problems such as gas leakage, deformation of the surrounding ground, and groundwater pollution. Therefore, visualization of the gasification zone of UCG is required for both improving gasification efficiency and developing UCG systems with low environmental impact. In this study, the large-scale model UCG experiments conducted on a laboratory scale (size: 625 mm × 650 mm × 2792 mm (H × W × L)) were carried out to discuss the visualization of the gasification reaction zone of coal in UCG by Acoustic Emission (AE) technique with uniaxial and triaxial acceleration transducers. As the results of temperature monitoring and AE source location analysis show, AE sources are located near the high-temperature zone (>1000 °C). In addition, the located AE sources move and expand with the movement and expansion of the high-temperature zone. AE measurement can be a useful technique for monitoring the progress of the UCG reaction zone. AE measurement with triaxial sensors is also useful to predict a high-temperature zone though the measurable range, which has to be considered. [ABSTRACT FROM AUTHOR]

Understanding the molecular structure characteristics of coal at the molecular level is of great significance to realize the rational utilization and efficient conversion of coal. This paper gives insights into the acquisition of characterization parameters of coal molecular microstructure by testing and analyzing the long flame coal from Qinggangping (QGP) Coal Mine through proximate analysis, ultimate analysis, vitrinite reflectance determination, fourier transform infrared Spectroscopy test (FTIR), X-ray photoelectron epectroscopy test (XPS), carbon nuclear magnetic resonance (13C-NMR) and X-ray diffraction (XRD). The results show that benzene rings in the QGP coal are mainly connected in a disubstituted way, accounting for 36.48%. Oxygen atoms mainly exist in the oxygen-containing functional groups such as the ether C–O, C=O and –COO. Aliphatic hydrocarbons in the aliphatic group are mainly of symmetrical -CHx stretching vibration. Hydroxyl groups are mainly composed of OH–OH and OH–O hydrogen bonds, accounting for 29.21% and 21.53%, respectively. Nitrogen atoms exist in the form of C4H5N. The coal molecular is mainly of aromatic carbon structure, where the ratio of bridge aromatic carbon to peripheral carbon is 0.198. There are benzene, naphthalene and anthracene in the coal molecular structure, and the former two chemicals play a dominating role. According to the analysis results, the molecular formula of the QGP coal is finally determined as C205H181O29N3S. On this basis, the two-dimensional and three-dimensional macromolecular models are constructed with the assistance of simulation software. In addition, the 13C-NMR spectra and densities of the constructed molecular models are calculated, which verifies the rationality of the models. The macromolecular structure model of bituminous coal constructed in this study provides a theoretical model basis for the optimal surfactant. [ABSTRACT FROM AUTHOR]

Underground coal gasification (UCG) is an important part of the low-carbon green coal mining technology system. With the implementation of the carbon peaking and carbon neutralization and the maturity of UCG, UCG will inevitably perform large-scale and industrialized production, which will certainly cause some issues such as serious waste of UCG sites caused by large-scale surface residual subsidence and poor foundation of fractured rocks. The key to the reuse of the surface site after UCG is to ensure that the surface residual subsidence does not exceed the design index of the building (structure). However, there is still a lack of methods for predicting residual subsidence on the surface of UCG. Under such background, combined with the characteristics of the UCG process, this paper analyzed the mechanism of the surface residual subsidence after UCG, and concluded that the root resource of the surface residual subsidence after UCG was the stripping and yielding of the hyperbolic coal pillars. Next, a calculation model of the maximum stripping width and yielding zone width of the "hyperbolic" coal pillar for UCG was established by the theoretical analysis method, and a method for predicting the surface residual subsidence with the consideration of coal pillar stripping and yielding was proposed and applied to Ulanqab UCG test site. The research findings have important theoretical and practical significance for the UCG site stability evaluation and land resource reuse. [ABSTRACT FROM AUTHOR]

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A multi-physics numerical method coupling fluid flow, heat transfer, and a chemical reaction was used to determine the temperature distribution and the conversion rate of a coal seam during underground pyrolysis. The coal seam was fractured to enhance the heat and mass transfer. The influences of the pyrolysis pressure on the heat transfer, oil and gas production, and pyrolysis time were also analyzed. When the injection gauge pressure was increased to 14 MPa, the conversion rate on the 120th day was 98.8% and the promotion was not obvious any more at further higher pressures for the model without a fracture. For the model with a fracture, the pyrolysis was completed in only 90 days at the much lower pressure of 4 MPa, which is beneficial for both reducing the heating period and enabling the rapid harvesting of oil. Then, the fractured zone was designed and optimized by investigating different radii of the fractured zone at both the inlet and the outlet of the domain. The dead zones around the two corners at the right side of the computational domain near the outlet well were reduced effectively with an increase in the diameter of the fractured region. The heat and mass transfer were enhanced with a larger area of the fractured region at the outlet well for the reason that the flowing dead zones experienced a longer effective heating time. [ABSTRACT FROM AUTHOR]

Fourier transform infrared spectroscopy (FTIR) was used to study the molecular structure of four medium- and low-temperature heat-treated medium-rank coals. The FTIR spectral parameters, which consist of CH2/CH3, aromaticity (fa), aromatic carbon rate (fC), aromatic hydrogen rate (fH), oxygen-containing (C–O) rate (IR), organic matter maturity (M), and the degree of aromatic condensation (Dc), indicate different characteristics, including changes in the aromatic hydrocarbon structure, fatty hydrocarbon structure, hydroxyl structure, and oxygen-containing functional groups of medium-rank coal. The results show that with the increase in heat treatment temperature, the sulfur content in coal gradually decreases, but the C/H ratio gradually increases. Meanwhile, the content of kaolinite and pyrite in coal gradually decreases, whereas the content of dolomite and hematite gradually increases. With the increase in heat treatment temperature, the relative content of ether oxygen hydroxyl groups in the hydroxyl structure significantly decreases, but the relative content of self-associated hydroxyl groups increases. The relative content of alkyl ether (C–O) in oxygen-containing functional groups gradually increases, whereas the relative content of aromatic nucleus C=C vibration presents a trend of first increasing and then decreasing. In addition, –CH2– is the majority in the structure of fatty hydrocarbons, and the absorption peak intensity of asymmetric –CH3 stretching vibration increases with the increase in heat-treated temperature. The structure of aromatic hydrocarbons mainly consists of four substituted benzene rings (except for R-303.15 K), in which the relative content of the trisubstituted benzene ring decreases with the increase in heat treatment temperature. With the increase in the heat-treated temperature of medium-rank coal, Dc, fH, fC, and fa show a trend of first increasing and then decreasing, M and IR reveal a trend of first decreasing and then increasing, and CH2/CH3 present a gradually decreasing trend. In conclusion, during the increase in the heat treatment temperature of medium-rank coal, the length of the fatty side chains in the fatty hydrocarbon structure becomes shorter, the number of branch chains continuously increases, and the maturity and condensation degree of organic matter first increases and then decreases. On this basis, further research on the effect of coal gasification suggests combining various technologies such as 13C NMR, XRD, and TG-MS to obtain semi-quantitative structural information of molecules in coal from different perspectives. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ethanolysis is an effective method to depolymerize weak bonds in lignite under mild conditions, which can result in the production of high-value-added chemicals. However, improving ethanolysis yield and regulating its resulting product distribution is a big challenge. Hence, exploiting highly active catalysts is vital. In this work, Fe2(MoO4)3 catalysts with zero-dimensional nanoparticles, one-dimensional (1D) nanorods, two-dimensional (2D) nanosheets, and three-dimensional (3D) nanoflower structures were successfully prepared and applied in the ethanolysis of Naomaohu coal. The results showed that for all samples, the yield of ethanol-soluble portions (ESP) was significantly improved. The highest yield was obtained for the Fe2(MoO4)3 nanorods, with an increase from 28.84% to 47.68%, and could be attributed to the fact that the Fe2(MoO4)3 nanorods had a higher number of exposed active (100) facets. In addition, the amounts of oxygen-containing compounds, such as ethers, esters, and phenols, increased significantly. The mechanism of ethanolysis catalyzed by the Fe2(MoO4)3 nanorods was also studied using phenylbenzyl ether (BOB) as a model compound. BOB was completely converted at 260 °C after 2 h. It is suggested that Fe2(MoO4)3 nanorods can effectively break the C-O bonds of coal macromolecules, thus promoting the conversion of coal. [ABSTRACT FROM AUTHOR]

Supercritical water gasification (SCWG) of coal provides a new solution for the green transformation and upgrading of traditional coal industry. Considering the good coal adaptability of SCWG and the excellent catalytic performance of K 2 CO 3 , a new kinetic model was developed in this work for predicting the catalytic gasification characteristics of coal of different ranks in supercritical water (SCW). In this model, various ranks of coal are characterized by the combination of three types of primary coal in different proportions, and the proportions can be obtained based on elemental analysis data and matrix computation. The SCWG of various ranks of coal can be considered as a combination of reactions of three types of primary coal in SCW. The model contains a total of 18 reactions, and various intermediates are represented by phenol and a high-carbon hydrocarbon. K 2 CO 3 -catalyzed SCWG experimental data of three different coal samples obtained in an improved quartz tube reactor system were used for the determination of model kinetic parameters. Then the experimental results of catalytic SCWG of other coal samples were used for the model validation, and it was found that the model can effectively predict the variations of gaseous products within an acceptable error. Afterward, the model was used to predict carbon gasification efficiency and gas compositions for coal of different ranks and to analyze carbon distribution and reaction rates for specific coal. The proposed kinetic model fits well with the good coal adaptability of SCWG technology, and it has great significance for the promotion of SCWG technology. • A general kinetic model of K 2 CO 3 -catalyzed supercritical water gasification of coal is developed. • Various ranks of coal are characterized by the combination of three types of primary coal. • Carbon gasification efficiency and gaseous products of coal of different ranks are compared. • Carbon distribution and reaction rates of gaseous products are analyzed. [ABSTRACT FROM AUTHOR]

This paper aims to describe methane adsorption in coal under the conditions of high temperature and high pressure, as well as quantitatively decipher the change rule of energy in the isothermal adsorption process. The isothermal adsorption test was carried out with four groups of middle-rank coals from the Linxing area with different degrees of metamorphism. The impacts of the degree of deterioration of coal, temperature, and pressure on adsorption were analyzed with regard to the adsorption amount, adsorption potential, and adsorption space. Additionally, the energy change during the adsorption of methane by the coal was considered. The results show that the coal adsorption capacity hinges on the degree of deterioration of the coal, as well as the pressure and temperature. Additionally, the impact of temperature upon coal methane adsorption under depth conditions is highlighted. Like the adsorption space, the adsorption potential is an important parameter used to quantitatively characterize the adsorption ease and adsorption capacity; furthermore, the adsorption potential of millipores exceeds that of mesopores, as they are capable of offering a larger specific surface area for adsorption. The total decrease in the surface free energy during adsorption increases as the pressure increases; simultaneously, the increase rate is fast and then slow. The total decrease in the above-described free energy diminishes as the temperature escalates. Under the same pressure, the total decrease in the aforementioned free energy increases as the reflectance of the specular body of the coal increases. The decrease in the aforementioned free energy at each point of pressure lessens as the pressure grows; notably, when the pressure is comparatively low, the reduction is very fast. As the pressure escalates continuously, the decrease speed is slow. Regarding the effect of pressure and temperature upon adsorption, the adsorption gas volume of coal exists in a conversion depth from 1200 m to 1500 m; at the same time, the impact of pressure upon adsorption is dominant up to this depth. Additionally, beyond this depth, temperature gradually comes to have the greatest impact on adsorption. [ABSTRACT FROM AUTHOR]

This document discusses the molecular structure of coal and its impact on methane adsorption. The complex composition of coal, including organic and inorganic matter, affects its adsorption capacity. Various experimental techniques, such as spectroscopy and microscopy, can be used to study the chemical structure of coal. The document also highlights several research papers that explore the pore structure and gas content of coal, providing insights for coalbed methane production and exploration. The authors of these papers are from China, reflecting the country's focus on coal research due to its abundant reserves. [Extracted from the article]

Fine coal reject samples (FCRs) derived from the South African (SA) feed-coal preparation are unsuitable for gasification/combustion. In this novel investigation, two SA FCRs were taken from a thermal-export plant (TEP) and steam-station (STEM) for the coal-property comparison study and pyrolysis/gasification reactivity. H2S/SO2/CO2/Cadmium/Arsenic/volatile organic compounds (VOCs) emissions/dust/particulate-matter pollution linked to pyrite-spontaneous combustion and the interaction of organic sulfur and calcium in FCRs are serious threats to the global human health and atmospheric environment. Numerous investigations primarily focused on SA unoxidized FCR (STEM sample) rather than oxidized FCR (TEP sample) and beneficiated fractions. Furthermore, no Raman/X-ray diffraction (XRD)/density-separation/thermogravimetric results for the TEP (40–400 µm; 83% recovery) and STEM (111–500 µm; 20% recovery) samples have been previously reported. FCRs/their beneficiated fractions were characterized by the different coal analyses. Results indicate that the FCRs have similar properties compared to gasification/combustion feed coals with the exception of higher mineral matter (39% versus 29%), higher vitrinites (43% against 24%) and higher alkali index (8 versus 5) in the TEP sample. Thermogravimetric gasification experiments illustrate higher reaction rates/higher carbon conversion for the TEP sample than the STEM sample. Raman/XRD detected aromatic/aliphatic hydrocarbons/minerals, which positively contribute to the coal's reactivity. Results provide a baseline toward FCRs utilization in pyrolysis/gasification applications on the basis of their reactivity, and a minimization of higher disposal-costs/health-hazards/air-pollution/fines volume. [ABSTRACT FROM AUTHOR]

[Display omitted] • A detailed mineralogical characterization study. • A feasibility study for the potential utilization of coal gasification ash. • First time study of a coal gasification waste generated from an Indian plant. • Optical and stereomicroscopy, FESEM with EDS, XRF, SEM-EDX, XRD, and TGA applied. This work aims to perform the applied mineralogical characterization of coal gasification ash (CGA) generated from a commercial fixed bed downdraft gasification plant in eastern India. Analytical and characterization techniques such as stereomicroscopy, optical microscopy, field emission scanning electron microscopy (FESEM) with energy dispersive spectroscopy (EDS) attached, X-ray fluorescence (XRF), energy dispersive x-ray spectrometer associated scanning electron microscope (SEM-EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) were applied for analyzing the coal and the corresponding gasification ash sample. These analytical techniques illustrate that SiO 2 and Al 2 O 3 are the major gasification ash phases, accounting for almost 85% of the entire CGA composition. The dominant mineral phases, such as quartz, mullite, and other aluminosilicates, provide an opportunity for utilization in construction and refractory material manufacturing. Moreover, confirming the presence of rare and valuable earth elements (RVEEs) in the CGA sample with SEM-EDX analysis unearths a new application window in meeting the requirement of the RVEEs starved nation like India, where very few commercial-scale coal gasification units are operational. [ABSTRACT FROM AUTHOR]

The authors of the study focused on the problem of hydrogasifying coal extracted from a particular location. Since hydrogen is transparent to radiation, it can only be heated by convection. To achieve this, we developed a swirler and utilized Fluent software (version 19.0) to simulate the primary flow vectors and the temperature distribution of hydrogen in the hydrogasification reactor. The process was carried out under varying conditions, including temperatures ranging up to 1173 K, pressures of up to 8 MPa, and gas flow rates between 0.5 and 5 dmn3 min−1. The results showed that the carbon reactivity of the char was high up to a certain level of carbon conversion. In this study, the kinetic equations of the hydrogasification process were developed based on the theory of active centers. The researchers also evaluated the kinetic constants at the maximum reaction rate for the analyzed chars. The analysis was conducted for four extreme cases of process parameters, which included temperatures of 973 and 1173 K as well as pressures of 6 and 8 MPa. The results showed that the maximum hydrogasification reactivity of chars could be accurately described using equations for both the first- and second-order reactions toward hydrogen. This was likely due to the use of a narrow pressure range of 6–8 MPa during the experiments. The kinetic equations developed in the study could be used to model the process on a technical scale. [ABSTRACT FROM AUTHOR]

The study on CO2 gasification behavior helps to promote the clean and efficient utilization of high-alkali fuels. The high-alkali fuels feature high contents of alkali metals, and sometimes they are also rich in alkali earth metals and iron. Though the influences of minerals on gasification characteristics have been extensively studied, few researchers have selected minerals based on the ash composition of high-alkali fuel. Moreover, the complex interactions among minerals could lead to inaccurate conclusions. In this paper, the CO2 gasification behavior of chars originated from one high-alkali biomass and three high-alkali coals was studied. The effects of principal minerals related to the high-alkali fuels, which were determined through the new plasma ashing method and traditional muffle ashing method, were also further evaluated via synthetic coal char. The synthetic coal char was free from any intrinsic minerals. The results indicate that the gasification reactivities of chars from high-alkali fuels are positively associated with the reaction temperature (900–1200 °C). The biomass char possesses the highest gasification reactivity, and three coal char samples are inferior to various degrees. The related chemicals offer their catalytic activities at 1000 °C in the sequence of K/Na-containing chemicals > Fe-containing chemicals > Ca-containing chemicals. The shrinking core model (SCM) and two-dimensional growth of nuclei model (2DGM) were chosen to conduct the kinetic analysis. The reaction constants of chars from different high-alkali fuels agree with their gasification behavior. Generally, the 2DGM is more suitable than SCM to predict the conversion of selected char samples. In most cases, the additions of chemicals increase the reaction constants. When Fe2O3 and CaCO3 are added into synthetic coal char, the SCM is more accurate to describe the gasification behavior at 900 °C, but the addition of Na2SO4 makes the 2DGM a better one. [ABSTRACT FROM AUTHOR]

The outbreak of COVID virus resulted not only in massive human deaths but also created huge waste disposal issues. Proper disposal of COVID waste is necessary. The conversion of these wastes into value‐added products such as syngas is beneficial to overcome energy scarcity issues. The Indian high ash coal (HAC) is nonreactive, and the co‐utilisation of HAC with these plastic wastes is advantageous to produce high‐quality syngas. In the present study, thermal treatment of overall gowns (OG) used during COVID by pyrolysis and gasification process was carried out under inert and reactive conditions with and without HAC at various operating temperatures. During pyrolysis, oil with a yield of 17% was produced under N2 conditions at 900°C, whereas a reduced oxygen content in the oil was observed (absence of C–O) under CO2 conditions. The co‐gasification of OG with high ash coal in the fuel mixture resulted in the heating value of syngas as high as 8.56 MJ nm−3. The calorific value of the syngas increases by 51.8% when OG content in the fuel mixture is increased to 20% because hydrocarbon content in syngas increases by 8.73 times. Thermogravimetric analysis showed that by adding OG, gasification initiated 35°C earlier as compared to HAC. The solid residue obtained by co‐gasification contains calcium in the form of CaO and CaCO3 due to COVID‐19 waste. The global warming potential of the syngas generated is reduced by 32% with the addition of OG to 20%. [ABSTRACT FROM AUTHOR]

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Using a newly developed experimental setup, the features and advantages of an autothermal single-casing atmospheric subbituminous coal fluidized bed air-blown gasifier, combining a combustion and gasification section, and mixing the dispersed phase (inert material, char) and heat exchange between them through an annular transfer device, have been revealed. To increase the efficiency of the gasifier, an experimental-computational method was developed find the conditions for optimal operation, combining changing the annular flow's geometry and regulating the primary air for gasification. A simple and reliable multizone thermodynamic calculation model makes it possible to predict the composition of char and syngas in the gasification section with acceptable accuracy. This method confirmed that a two-section fluidized bed gasifier can provide efficient gasification of solid fuels and is suitable for use in small-scale cogeneration plants. Syngas with a heating value of 3.6–4.5 MJ/m3 and CGE of 38.2%–42.3% was obtained in the experimental setup without optimizing the primary air flow rate. With optimization, the indicators increased to the heating value of syngas of 5.20–5.34 MJ/m3 and CGE of 42.5%–50.0%. With heat regeneration of 0.8, CGE increases to 70%. [ABSTRACT FROM AUTHOR]

Underground Coal Gasification (UCG) requires monitoring of the gasification area because the gasification process is invisible and the reaction temperature exceeds 1000 °C. Many fracturing events that occurred due to coal heating can be captured with Acoustic Emission (AE) monitoring technique during UCG. However, the temperature conditions to generate fracturing events during UCG have not yet been clarified. Therefore, the coal heating experiment and small-scale UCG experiment are conducted by measuring the temperature and AE activities in this research to examine the applicability of the AE technique instead of temperature measurement as a monitoring method during UCG. As a result, many fracturing events are generated when the temperature of coal is changed drastically, especially during coal gasification. Besides, AE events increase in the sensor near the heat source and AE sources are expanded widely with the expansion of the high-temperature region. AE monitoring is an effective technique for the estimation of the gasification area during UCG instead of temperature monitoring. [ABSTRACT FROM AUTHOR]

The addition of biomass such as straw in the coal gasification process is one of the strategies for clean and efficient utilization of coal with decreasing CO2 emissions. However, the abundance of chlorine and alkaline metals contained in the corn straw is the key factor to aggravate the corrosion, deposition, and slagging of the co-gasifier. The effects of temperature (700–900 °C), residence time (2–12 min) and the addition ratios of corn straw on the migration behavior of Cl are studied during co-gasification of Shenmu coal and corn straw. The results show that the released amount of Cl from coal increases with the increase in gasification temperature and the extension of gasification time, while the amount of Cl in the coal gasification residue decreases initially and then stabilizes. On the other hand, the released amount of Cl from the corn straw increases with the increasing temperature and the extension of time below 800 °C, but both the temperature and time extension show limited effect on the released amount of Cl above 800 °C. It is also identified that the migration and volatilization behavior of Cl is related to the mass proportions of coal and biomass during the co-gasification process. When the addition ratios of corn straw are 16.7% and 50%, the released amount of Cl from the coal-biomass mixtures can be inhibited, while the released amount of Cl can be promoted when corn straw is added to coal-biomass mixture at the ratio of 37.5%. [ABSTRACT FROM AUTHOR]